1. Field of the Invention
The present invention relates to a liquid crystal display device and a manufacturing method for the same.
2. Description of the Related Art
As is advantageously slim, light in weight, and low in power consumption, a liquid crystal display device has been popular as a display device being applicable to various many uses. The liquid crystal display device is recently used widely, including a large-sized television receiver for home use and a small-sized mobile phone, and thus the demand for the properties of the display device, especially the demand for the viewing angle thereof is getting tough.
In consideration thereof, proposed are previous TN (Twisted Nematic) mode and IPS (In-Plane Switching) mode (e.g., refer to Patent Document 1 (JP-B-63-21907)) and a multi-domain VA (Vertical Alignment) mode (MVA) (e.g., refer to Patent Document 2 (JP-A-10-186330), for example.
Among these modes, the VA mode typified by the MVA mode is of high in productivity with easy acquisition of high contrast and wide control margin of a cell gap, for example, because liquid crystal molecules are vertically aligned with respect to substrates. Patent Document 3 (JP-A-2005-266778) describes a method about the alignment control over liquid crystal molecules utilizing oblique electric fields attained by providing a dielectric member to a pixel portion as a means for alignment-division, or forming notches and slits to transparent electrode portions of the pixels, e.g., ITO (Indium Tin Oxide).
With such a method, as shown in the schematic plan layout of FIG. 10A and in its main-part cross sectional view of FIG. 10B, liquid crystal molecules 22 can be aligned radially around an alignment control element, e.g., dielectric member, 34 that is provided to a pixel electrode (common electrode) 32 in a sub-pixel 50. This is achieved by forming a notch to the pixel electrode 32 and a pixel electrode 12 in a pixel 40, thereby dividing the pixel 40 into a plurality of sub-pixels 50 (51, 52, and 53). To each of the resulting sub-pixels 50, the alignment control element 34 is disposed on the pixel electrode 32 located opposite to the pixel electrode 12 to be at the center of the sub-pixel 50. With the radial alignment of the liquid crystal molecules 22 as such, any perceivable change of intensity from the direction of the azimuth angle is reduced, thereby deriving properties of wide viewing angle.
For dividing a pixel into a plurality of sub-pixels, however, there needs to establish an electrical connection among the sub-pixels. The method described above is thus making an attempt to leave a pixel electrode (common electrode) at the center portion of each of the sub-pixels. In this method, in the sub-pixel, an alignment control element provided to an opposing electrode takes charge of controlling the alignment direction. The problem with such a method is that the alignment control applied to the portion of electrical connection is weak. Therefore, when a liquid crystal panel is pushed, for example, the alignment of liquid crystal molecules is once lost as shown in the photo example of FIG. 11B. In FIG. 11B example, the liquid crystal molecules in the portion of electrical connection are pushed in the direction different from that before the push. The alignment of the sub-pixels is thus also lost, thereby resulting in poor alignment. As shown in the photo example of FIG. 11A, when the surface of the liquid crystal panel is not pushed, no misalignment is observed.
That is, as shown in FIGS. 10A and 10B, in a pixel, an electrical connection is previously required to be established among pixel electrodes (portions of connection) between sub-pixels. However, in the method above, no element is provided for defining the alignment in the portion of connection, whereby the state of alignment is not stable. When the alignment of the liquid crystal molecules is once lost without much choice with a push on the surface of the panel, for example, the alignment is never recovered back to the former condition.
FIG. 12 schematically shows an exemplary misalignment. The misalignment occurred to the liquid crystal molecules 22 is not recovered as such, observed on the panel is a phenomenon of abnormal display with a trace of misalignment. The degree of display abnormality can be reduced by disposing the sub-pixels 50 away from one another, but the longer distance among the sub-pixels 50 causes another problem of reducing the transmittance.